The present application relates generally to optical medical sensors, and in more particular relates to fiber-optic oxygen saturation sensors.
Traditionally, fiber-optic oxygen saturation sensors have taken the form of two or more optical fibers mounted parallel to one another within a catheter. Red and infrared light are applied to the proximal end of one of the fibers, and are emitted at the distal end of that fiber. The red and infrared light is reflected by the bloodstream, and enters the distal end of the second optical fiber. Light exiting the proximal end of the second fiber is measured in order to determine the relative intensities of reflected red and infrared light. Such a measuring system is included in U.S. Pat. No. 4,776,340, issued to Moran et al, included herein by reference in its entirety. While single optical fiber sensors are known for use in conjunction with measuring chemical parameters of the blood, such as pCO.sub.2, pO2 and pH, fiber-optic reflectance oximeters have typically employed two or more fibers.
Optical hematocrit detectors have traditionally employed two light sources and a single detector or two detectors and a single light source to provide two different source to detector spacings. As translated into a fiber-optic hematocrit sensor, this has resulted in the construction of hematocrit detectors employing three fibers. One such hematocrit detector is disclosed in the above cited Moran et al patent.